Explained: What we know of 2019 Novel coronavirus

Coronavirus outbreak: The virus, which has also reached India, has been declared a global health emergency. A look at how much is understood about the outbreak so far, and how much information is still emerging

Explained: What is a coronavirus?

Coronaviruses are a class of viruses so named because their electron microscope image resembles the corona of the sun. Coronaviruses are usually found in animals, but sometimes get transmitted to human beings possibly through the food chain. This happened during the 2003 outbreak of SARS (Severe Acute Respiratory Syndrome), which too was caused by a coronavirus and originating in China, and which had claimed close to 800 lives. The coronavirus strain involved in the current strain too is getting transmitted to humans. The strain has tentatively been named 2019 ‘novel’ coronavirus, or 2019-nCoV.

Since the outbreak was detected about a month ago, scientists have been able to piece together considerable amount of information about the origin, transmission and lethality of the 2019-nCoV, but several questions are still being investigated.

What are coronavirus symptoms, and how dangerous is the infection?

Like other coronaviruses, 2019-nCoV manifests itself initially in the form of mild fever and cough, and affects mainly the respiratory system in human beings. Not more than one-fifth of the infected people are likely to develop severe illnesses. Hong Kong-based Professor Malik Peiris, who had played an important role in identifying SARS in 2003, said the nCoV seemed to be more easily transmissible than SARS but was less dangerous.

According to an information dashboard put up by Johns Hopkins University, last updated at 8 am India time on January 31, there were a total of 9,776 confirmed cases of nCoV, of which 213 had resulted in deaths, giving a mortality rate of just over 2%. The mortality of SARS was considerably higher, closer to 10%, at 774 deaths from 8,096 confirmed cases.

“This means that in nCoV, individual risk of getting infected is reasonably high, but severe disease in infected people is not inevitable,” says Dr Gagandeep Kang, executive director of Faridabad-based Translational Health Science and Technology Institute. The Johns Hopkins dashboard also shows that a total of 187 infected people had already been declared fully recovered.

At a screening desk for coronavirus.

Where did coronavirus originate?

An analysis of 10 genome sequences of nCoV from nine patients in Wuhan, published in The Lancet, has revealed that the virus was closely related to two SARS-like coronaviruses usually found in bats. Another study in the Journal of Medical Virology suggests that nCoV could have jumped from bats to snakes before infecting human beings.

The first patients in Wuhan were found to have visited a local wholesale seafood market, where live animals, including snakes, too are sold for meat. However, how and when the nCoV first entered the human body is still an open question for investigation.

How does coronavirus transmit itself?

Respiratory viruses, like those that cause colds, flu, and pneumonia, spread mainly through coughs, sneezes and direct contact with infected people. In most such cases, the transmission of the virus happens only after an infected person has developed the symptoms. This was true of SARS as well. The spread of such viruses is relatively easier to contain, because people with symptoms can be quarantined.

Initially, nCoV too was believed to have a similar trait. But a new study, published in The New England Journal of Medicine on Thursday, has documented the first case in which the virus was transmitted from one person to the other, even before the symptoms had become evident in the first person. Such transmissions are called asymptomatic.

A Chinese woman, who had travelled to Munich, passed on the virus to her German business partner a couple of days before she herself showed any symptoms.

In another study in the same journal, this one published on Wednesday, researchers analysed data on the first 425 confirmed cases and found that each one of them had spread the infection to an average of 2.2 people. In general, any epidemic would continue to spread as long as this number, called reproductive number and referred to as R-naught, is greater than one. In the case of SARS, it was 3.12, but there was no asymptomatic transmission happening, and patients could be isolated. Now, asymptomatic transmission can complicate the efforts to contain the spread of the virus.

WHO says coronavirus a global health emergency. What does this mean?

The declaration of the nCoV outbreak as a Public Health Emergency of International Concern (PHEIC) by the WHO is aimed at halting the further spread of the epidemic. The WHO has asked all countries to be prepared for containment, active surveillance, early detection, isolation, and tracing of contacts of infected people. Countries would now have to mandatorily share all such data with the WHO.

The declaration of PHEIC shows that WHO considers nCoV a significant public health threat outside China as well, requiring a coordinated global response. WHO, however, has not recommended any travel or trade restrictions on China, though several countries have put out their own travel advisories. A few countries have even closed their borders with China, while some airlines have stopped flights to Chinese cities.

A global health emergency was first declared in 2009 during the time of H1N1 flue pandemic. Other instances of PHEIC being declared happened in 2014 for the Ebola virus spread, and in 2016 for the Zika virus outbreak.

What precautions should one take to prevent coronavirus infection?

The most effective way of prevention is avoidance of contact with an infected person. Making sure that infected people use cough hygiene — covering nose and mouse while they cough and sneeze, disposal of tissues or handkerchief carefully – and wash and rinse their hands properly is thus very important.

There is no approved vaccine for the disease, neither is any antiviral treatment available as of now.

But diagnostic tests have been quickly developed. “Because of the early sharing of gene sequence data by Chinese authorities, it was possible to develop diagnostics as well as identify vaccine targets. WHO is coordinating research and development efforts for nCoV diagnostics, therapeutics and vaccines. A global partners meeting will be held for this purpose in mid February,” said Dr Soumya Swaminathan, chief scientist at WHO.